<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>jquery入门</title>
</head>
<body>
<span id ="sp">jquery</span>
</body>
<script src="js/jquery-3.3.1.min.js"></script>
<script>
    let $jq=$("#sp").html();
    alert($jq);
</script>
</html>